Dehydrating apparatus



May 18,- 1943 H, Q FRENCH A l 2,319,673

DEHYDRATING APPARATUS Filed Feb. '7, 1941 2 Sheets-Sheet l- INVENTOR MGM . AT TORNEY.

May 18, 1943 HJC. FRENCH 2,319;673

f l DEHYDRATING APPARATUS Filed Feb. 7, 1941 2 sheets-sheet 2' l@ INVENTOR y S2 /veam/ki ATToRNEv.

Patented May 18, 1943 DEnYDnA'riNG APPARATUS Henry C. French, Elm Grove, Wis., assignor to Arnold Dryer Co., Milwaukee, Wis., a. corporation of Wisconsin .Application February 7, 1941, serial No. 377,798

(cl. 263-32)l 17 Claims.

This invention relates to improvements in dehydrating apparatus.

It is a general object of the present invention to provide an improved dryer which can be furnished in such size as to be portable, and which will eiliciently handle large quantities of forage crops or the like and rapidly and continuously .dry such material with a minimum loss of nutrients and color and with a minimum expense for fuel.

A more specific object of the invention is to provide an eilicientdryer of the class described embodying a rotatable cylinder wherein'the combustion chamber is rotatable with said cylinder and effectively supported therein on longitudinal spacers forming a combustion chamber pocket.

A further object of the invention is to provide an improved dryer having means for admitting air inregulated quantities into the mixing chamber through passageways extending longitudinally of the combustion chamber on the exterior thereof and between the longitudinal combustion chamber supporting spacers.

A further object of the invention is to provide in a dryer having a rotatable cylinder with a combustion chamber therein, means for returning hot gases of combustion together with steam from the exhaust outlet of the apparatus to the mixing chamber, the arrangement being such that said returned steam is superheated before being discharged into the mixing chamber. Thus economy in operation is effected because of reclaiming the used gases of combustion. Furthermore, superheated steam is a more efficient drying medium'than air, and the re-circulation of said steam eliminates the necessity of admitting free air in as large quantities as would otherwise be required, and'thereby reduces the oxygen content in the dryer.

A further object of the invention is -to provide apparatus as above described wherein the admission of used gases and steam to the mixing chamber is Athrough a common'passageway with the free air and under the control of the air admission regulator, the arrangement being such that the amount of used gases and 'steam admitted is inversely proportional to the amount of free air.

Other objects of the invention are toy provide may be performed by a positive screw feed:

'wherein the housing for the screw feed rotates with the cylinder and has a slip joint connection with the material receiving hopper; wherein there are a number of intercommunicating, concentric cylinders with spiral ballles arranged on the outer surfaces of the inner cylinders to most effectively advance the material and agitate the air circulating in each cylinder; wherein there are lineal conveyor flights on the inner surface of the cylinders; wherein the outer cylinder is effectively insulated against loss of heat; wherein the concentric cylinders are eiectively connected and spaced by means of radial straps or the like; and-wherein the outer cylinder is formed with circumferential tracksV cooperable, p

with flanged rollers on the supporting structure or carriage to effectively support the cylinder for rotation.

With the above and other objects in view, the invention consists of. the improved dehydrating apparatus and all its parts and combinations,l as set forth in the claims, and all equivalents thereof.

In theaccompanying drawings illustrating lone complete embodiment of the preferred form of the invention, in which the same reference numerals designate the same parts in' all of the views,

Fig. 1 is a side elevational view of the improved apparatus, parts being Abroken away, and part f of the apparatus being shown in longitudinal secof Fig. 1;

Fig. 4 is a side elevational view of the piping arrangement for handling the exhaust gases, in-

cluding the dry material collector, part of the associated dryer apparatus being shown in dotand-dash lines;

Fig. 5 is a front view on an enlarged scale of the mechanism for admitting regulated quantii ties of free air and exhaust gases;

Fig. 6 is a fragmentary sectional view taken on line 6-6 of Fig. 5; and

Fig. 7 is an edge view of a portion of the structure shown in Fig. 5, with the exhaust gas hood and outer band omitted. l

Referring more particularly to the drawings, the numeral I0 designates the frame of a suitable supporting structure, which preferably takes the form of a carriage having front wheels l I and rear Wheels I2 whereby the dryer is readily portable. Depending from the front of the frame Il is a support I3 for a fifth wheel I4, whereby thev front axle Il is suitably supported for steering movement. The front axle I5 is relatively short so as to clear the drop frame portion i4 to the rear thereof during steering movement. The supporting frame l0 is equipped with a pair of flanged rollers I1 on each side, the rollers being keyed to a shaft I8 which is journalled in bearings Il. The rollers I1 cooperate with circumferential drive bands 2li on the outer side of an outer cylinder or drum 2|. be rotated by transmitting rotation of one of the roller shafts I2, or in any other desired manner.

Arranged in spaced relation from each other and` from the outer drum 2l are inner concentric drums 22 and 2l. At one end of the appa- The drum may ratus the drums are connected to each other and suitably spaced by means of radial straps 24.

The outer ends o f these straps are braced against and suitably connected to llineal conveyor flights 2| and 2l on the inner surfaces of the outer and intermediate drums, as indicated at 21. The inner ends o'f the straps are flanged and connected to the outer surface of the adjacent drum,

as at 24. At the other end of the apparatus there is a housing 3l for a spiral conveyor feed Il. The housing' II extends axially of the drums 22 and-23 through the end opening 32 of the intermediate drum where it is welded to the edges of said opening, and into the open end of the inner drum 2:. The drum zz 1s connected to the drum 2| byv a plurality of radially extending gussets I2 and a plurality of radially extending gussets 32! on the inside of the drum 22 support a ring 29 within which the end of the innermost drum 2l is slidably supported. In addition a conical discharge guide 34 connects the exterior of the spiral conveyor housing ll with the end of the intermediate drum 22' to -firmly support the conveyor housing. The conical discharge guide directs material being discharged from the outer4 drum toward the end discharge opening. 3B in y said drum.

Wet material to be dried, which material has previously been 'cut to desired length, is introduced by any suitable lmeans into a. hopper II, which hopper is suitably supported on the frame I0. The bottom of the hopper communicates with an opening 31 in a xed housing portion 34 for the spiral feed conveyor 2l. The conveyor housing portion 30 is secured to and rotatable with the drying drums, and there is a slip joint Il between the outer end of the rotatable hous- I -charged radially of the inner drum 2l, as indicated by the arrow in Ilig.` 1, from between the supporting arms 42 of a spider 42, which spide has an asbestos shield as at 4I'.

At the opposite end of the apparatus the innermost druni` has secured to its inner surface longitudinally extending circumferentially spaced I-beams or spacers 44 which form a pocket for structed of refractory material or heat resisting `metal such as cobalt steel. The I-beams 44 provide longitudinal spaces or passageways 4! exteriorally of the combustion chamber, which serve to cool the latter and also form ducts for the admission of free air and returned gases and steam, as will hereinafter be described. The steam in passing through the passagewa'ys 4l becomes superheated before being discharged into the mixing chamber 4l.

The inner end of the combustion chamber is open, as at 4l, so that the hot gases of combustion are discharged Ainto the mixing chamber 41. The outer end of the combustion chamber is formed with a relatively small inwardly flared opening 49, which is in registration with the nozzle 50 of an oil burner 5i or other suitable source of heat.

The oil burner nozzle 50 extends axially into the open end of a cup-shaped member 52, said member having its inner end secured to the outer end ofthe combustion chamber 4l and having an opening 53 in registration with the flared opening 49 (see Fig. 6). Spaced outwardly from and concentric with respect to the peripheral wall 54 of the cup-shaped'member I2 is a ring 55 having external circumferential flanges Il (see Figs. 6 and 7). The ring l5 is secured to the end wall of the outer drying drum as at Il. 'Ihus an annular space Il is formed between the ring Il and the peripheral wall 54, which space is in registration with the passageway: 4I surrounding the combustion chamber. Free air may be admitted to the annular space Il through ports 59, which ports can be closed completely or opened to a desired extent by means of a ring damper Il having ports Il which may be made to partially or completely register with the ports I9. The damper ring may be held in adjusted. position by bolts I2 cooperable with arcuate slots I l.

lThe assembly of the cup-shaped member I4, ring 85, and combustion chamber cylinder 4l is therefore rotatable with the drying drums andf some of the peripheral openings 640m the ring 55 are always in registration with the curved lower end of a hood il. 'I'he lower end of the hood has flanges il (see Fig. 6) which fit between the flanges B8 of the ring l5. The openings 44 in the ring $5. which are not in registration with the hood, are always closed by a band l1 which has its ends bolted to the ends of the hood as at 88. The band $1 also fits between the flanges l. of the ring II.

With this construction. used gases and steam which are returned through the pipe I enter the hood and pass through the openings 44 into the annular space Il, and from the space slidably receiving. a combustion chamber form- Il through the longitudinal passageways 4I around the combustion chamber into the mixing chamber. When the circular damper 44 is in the position of Fig. 5, free air from the outside will also be admitted. The Awider the damper Il isopen to admit free air, the less flue gases and steam which will be drawn through the hood Il. Conversely, by limiting the size of the air openings, or by closing the same entirely through adjustment of the damper Il, a greater amount of ilue gases and steamwill be drawn into the mixing chamber of the dryer.

The movement through the drums is created by the action of a suitably driven exhaust fan 1l mounted in a housing 1|, which housing has an opening 12 communicating with the conduit 12. I'he conduit I I'has its upper endsurround ing the'housing 30 for the spiral conveyor and extending horizontally into the discharge opening 35 of the outer drum 2l, the drum being rotatable around said portion of the conduit 13.

When the blast of hot gases entering the combustion chamber 45 from the nozzle 50 together with air drawn in around the nozzle, as indicated by the arrows in Fig. 1, is discharged into the mixing chamber 41, it is mixed with free air, use'd gases of combustion, and steam, which enter the mixing chamber 41 from the passageways 46 surrounding the combustion chamber.` If the air damper 60 is shut off completely, only used gases and steami will enter from the passageways 46. The steam as it passes through the passageways 46 is superheated, and Vthe used as heretofore exdirected back into the dryer plained.

From the above it is'clear that a relatively inexpensive, portable dryer has been provided wherein the combustion chamber is contained within and is rotatable with the dryer cylinders. Novel `means, is also provided for admitting free air and returned gases and steam .to the dryer through passageways on the exterior of a rotating combustion chamber. The method of introducing the wet material into the dryer provides a seal, formed by the material itself,

gases are additionally heated; also the temperaf ture of any free air admitted is raised substanv tially before said air is discharged into the mixing chamber.v This passage of gases, steam, and free air through'the passageways 46 also tends to keep down the temperature of the combustion chamber cylinder 45. Into this mixture of gases the wet material to be dried is discharged radially, as indicated by the arrow in Fig. 1, from the periphery of the spider 43.' In the rotation of the inner drum particles of vmaterial to be dried which drop to the bottom of the drum are carried by the lineal flights 14 to the top of the drum where they fall Vthrough the blast of hot gases. 'The lighter particles will be advanced through the drum by the blast of 'gases more rapidly than will the heavier particles. The gases and partially dried material pass out of the discharge Aencl of the inner drum 23 and 2:--

into thespace between said inner drum and the intermediate drum 22. This movement is caused by the action of the exhaust fan. The

outer surface of the inner drum 23 is provided with spiral baffles 15 which serve to mechanically advance the material and also cause the gases to be agitated in the space between the cylinders to more effectively extract moisture from thel material. The heavier particles of material between the drums 22 and 23 will fall to the bottom of the drum 22 and be lifted by the lineal flights 26. These ights will carry the material upwardly as the drum rotates, to again drop the material into the stream of hot gases. From the discharge -end 16 of the intermediate drum the gases and material passinto the ,space between the outer drum'l and intermediate drum 22 and'travel -iri a' reverse'direction, as indicated by the arrows.

While traveling through the outer drum the material andl gases are acted upon by the spiral balles' 11 on the outer surface of the intermediate against admission of undesired free air, and the material is discharged in a radial -direction into the mixing chamber in a position to be most effectively acted upon by the hot gases. By

having the feed hopper at the same end of the dryer as the discharge, a thermometer 83 may Ibe used at the outlet passageway so that the machine may be fed by watching the ther` vit has had an opportunity to become -wilted by exposure. The structure ofthe apparatus is such that the hay is subjected to the proper amount of heat so that it is dried quickly, uniformly, and economically with a minimumloss of nutrients and color.

In the claims the term gases as used to-define the matter directed through'the passageways 44 adjacent the exterior of the combustion chamber contemplates not only used gases of combustion but also any of the other gases directed through said passageways such as air,l steam, or any combination of said gases.'

While the use of a plurality of concentric drums is highly desirable, many of the features drum 2,2 and by the lineal lflights 25; The stream of gases and material is ultimately directedby the conical discharge guide 34 into the passageway 13 where it passes through the fan housing v1I and out through a discharge pipe18.

The discharge pipe 18 communicates with a collector 19 (see Fig. 4), and arranged concentrically Within the collector is a cylinder 80-which is open at the top, as at 3 I and also at the bottom, as at 32. The material and gases first pass in `a circular path around the. cylinder 80 and the dried material falls out of the bottom of the collector 19 into a suitable receptacle. The used gases pass into the lower end 82 of the `cylinder 30,. andvsome of said gases are discharged out of the upper end 8l. A certain amount of these gases and steam, depending upon the position of of this invention are obviously applicable to dryers comprising a single drum only and, therefore, while;only--one.`fform of` constructionfthas `been shown and described, various changes and modifications may be' made without departing from the spirit of the invention, and all of such changes are contemplated as may come within the scope of the claims.

I claim: f

1. In a dehydrating apparatus, a rotatable drying drum, a combustion' chamber unit extending into one end of said drum and rotatable the air regulator 60 (see Fig. 5), is re-circulated through the conduit 69 to the hood i5 to be therewith, means for delivering hot gases of combustion into said rotatable combustion chamber, said drum having an' intermediate mixing chamber into which hot gases of combustonare discharged from the combustion chamber, means including passageways extending adjacent the exterior of the combustion chamber unit for directing gases into said mixing chamber beyond the combustion chamber unit, means for feeding wet material into said mixing chamber from the opposite end of said drum to be acted upon by the hot gases therein, andmeans for discharging dried material.

2. In a dehydrating apparatus, a rotatable drying drum, a combustion chamber unit extending into one end of said drum andl rotatable therewith, means for delivering hot gases of combustion into said rotatable combustion chamber, said drum having `an intermediate' mixing chamber into which hot gases of combustion are discharged from the combustion chamber, means including passageways extending adjacent' the exterior off the combustion chamber unit for directing free air and used gases directly into said mixing chamber, means for feeding wet material into said drum to be acted upon by the hot gases therein, and means for discharging dried material.

3. In a dehydrating apparatus, a rotatable drying drum, a combustion chamber unit extending into one end of said drum and rotatable therewith, means for delivering hot gases of combustion into said rotatable combustion chamber, means for intercepting used gases of combination, means including passageways extending adjacent the exterior of the combustion chamber imit and substantially surrounding the same for directing said re-circulated gases which have already acted upon material back into said dryer beyond the combustion zone, means for feeding wet material into said drum to be acted upon by the hot gases therein, and means for discharging dried material.

4. In a dehydrating apparatus, a rotatable drying drum, a combustion chamber unit extending into one end of said drum and rotatable therewith, said'drum having a mixing-chamber inwardly of said combustion chamber unit, means for delivering hot gases of combustion asiaors tending into one end of said drum and rotatable therewith, means for delivering hot gases of combustion into said rotatable combustion chamber, means for delivering wet material into the opposite end of the drum to be acted upon by the hot gases therein, and means at said end of the drum for discharging dried material and used gases.

8. In a dehydrating apparatus, an outer rotatable drum, at least one smaller drum within said outer drum and communicating therewith, said smaller drum being rotatable with said outer drum, means for delivering hot gases into one oi said drums, an end of said outer drum having a discharge opening, a screw feed conveyor including a tubular housing portion extending into said discharge opening of the outer drum and into an end of an inner drum therein, externalmeans for rotatably supportfor rotation with the drums, means providing an into said rotatable combustion chamber, means for re-circulating gases which have already acted upon the material, means for directing said gases back into the mixing chamber of the dryerI Vwhile the latter is rotating and beyond the inner end of the combustion chamber, means for feeding wet materiallinto said dryer to be acted upon by the hot gases therein, and means for discharging dried material.

5. In a dehydrating apparatus, a rotatable drying drum, a combustion chamber unit extending into one end of said drum and rotatable therewith, meansior' delivering hot gases of combustion into said rotatable combustion chamber, means' including passageways extending adjacent the exterior of the combustion chamber unit for directing used gases including steam back into said dryer yand for discharging said gases inwardly of the combustion zone,

vwhereby the steam is superheated by contact chamber, a screw I-feed conveyor including a tubular housing portion, said conveyor and housing extending into the opposite end of the drum land the housing being rotatable therewith for deliveringwet material into the stream of hot gases within the drum, an external feed hopper,

said rotatable tubular housing portion having a slip Joint connection with said hopper, and

means for discharging dried .material from ythe 7. a dehydrating apparatus. a rotatable drying drum. a combustion chamber unit exoutlet from said smaller drum around said tubular housing DOrtion, and means for discharging dried material irom the outer drum around said tubular housing portion.

9. In a dehydrating apparatus, an outer rotatable drum. a smaller drum within said outer drumand rotatable therewith to provide a passageway between the inner and outer drums, means for delivering hot gases into the inner drum, means for delivering wet material into said inner drum, balnes on the exterior of said inner drum shaped to agitategases and material passing between the drums and to aid'in the advancement ofsaid gases and material,

and means for discharging the dried mater-idr l0. In a 'dehydrating apparatus, an outer rotatable drum, a smaller drum within said outer drum and rotatable therewith to provide a passageway between the inner and outer drums, means for delivering hot gases into the inner drum, means for delivering wet material into said inner drum, spiral Vbaiiies on the exterior of said inner drum shaped to agitate gases and material passing between the drums and to aid in the advancement ot said gases and material, and means for discharging the dried material.

11. Ina dehydrating apparatus, an` outer rotatable drum, a smaller drum within said outer drum and rotatable therewith to provide a passageway between the inner and outer drums, means for delivering hot gases into the inner drum, means for delivering wet material into said inner drum, baiiies on the exterior of said inner drum shaped to agitate gases and material passing between the drums and to aid in the advancement of said gases and material,

lineal flights on the inner surface of the outer drum forlifting material during the rotation of the drum and for dropping the same into the current of gases and onto the exterior of the inner drum to be acted upon by the baiiies, and means for discharging dried material from the 12. In a dehydrating apparatus for forage crops or the like a rotatable drying drum having a combustion zone 4portion adjacent one end and within the drum, means for delivering hot gases of combustion into said combustion zone portion, said drum having a mixing chamber portion inwardly of said combustion zone portion, means for feeding wet material into said drum at a location other than the combustion zone portion, meansincluding passageways extending adiacent the exterior of the combustion zone portionfor directing gases having a 1 reduced oxygen content into said mixing chamrial into said drun to be acted upon by the hot dryins 5 i5. Ina dehydratingapparatus. a rotatable tending into one end of said drum and rotatable therewith, means for delivering hot gasa of combustion into saidrotatable combustion chamber, means including passageways extending adjacent the exterior ofthe combustion chamber unit for directing gases into said dryer beyond the combustion chamber unit, said combustion chamber unitbeing substantially surrounded by said passageways to provide for subgases therein, and means for discharging the dried material.

13. In a dehydrating apparatus for forage crops or the like, a rotatable drying drum hav- -ing a combustion zone portion adjacent one end, means for delivering hot gases of combustion into said combustion zone portion, said 1 drum having a mixing chamber portion inwardly of said combustion zone portion, means for feeding wet material intosald drum at a location other than the combustion zone portion, ran exhaust fan .for creating 'a current of drying gases to convey the material through said drum, and means for admitting gases in addition to those from the combustion soneto said mixing chamber inwardly of the combustion zone to supply gases for said current.

14. In a dehydrating apparatus, a rotatable drying drum, a combustion chamber unit extending into one end of said drum and rotatable therewith, means for delivering hot gases of combustion in to said rotatable combustion chamber, means including passageways extending adjacent the exterior of the combustion chamber unit for directing gases into said dryer beyondthe combustion chamber unit, said passageways being lpositioned and arranged to provide for substantial cooling of the combustion chamber by the gases moving through said passageways, means for feeding wet material into said drum to be acted upon by the hot gases therein, and means for discharging dried material.

gtantial cooling of the combustion chamber by the gases moving through said passageways,A

y means for feeding wet material into said drum the housingv to be acted upon by the hot gases therein, and means for discharging dried material.

16. In a dehydrating -apparatus, a rotatable i drying drum, means for delivering hot gases of combustion into one end of said rotatable drum,

a screw feed conveyor including a tubular housing portion, said conveyor and housing portion extending into the opposite end ot the drum and being rotatable therewith for delivering wet material into the stream of hot gaseawithin the drum, an external feed hopper, said rotatable tubular lhousing portion having a slip Joint connection with said hopper, and

means for` discharging dried material from ,the

drum, means for delivering hot gases of drying combustion into one end o! said drum, means for delivering wet material into the opposite end vof the drum to be acted upon by the hot gases therein, means at said last mentioned end of `the drum for discharging dried material and 'rial is being delivered -into the saine end of the v v 1 .HENRY C.FRENCH.

drum, a combustion chamber unit ex- 3., 17. In a dehydrating apparatus, a rotatable. 

